Idles great, but bogs above 1/2 throttle

[WhoIsJohnGalt]

IF you saw my other post, you know I'm a novice and know that I just rebuilt the carburetor on my Max IV with Kawa FD750D engine. It now idles great and revs up nicely until I get the throttle above about 1/2 way then starts to "bog down". Not sure if it is a fuel issue or an air issue, but if I pull on the choke with the higher throttle it will run much better. I have tried adjusting the screw thingys - two on top of the carburetor with plastic limiters on top and two embedded in the sides of the carburetor with small holes drilled through them. I did mark the starting locations for them and have been trying to tweak one at a time--they only seem to affect the lower throttle levels and idle, but at higher throttle those settings don't really make much difference.

Is it an air problem? Fuel problem? It seems to me its a lack of air flow at higher throttle but not sure what to do to troubleshoot that.

Any thoughts, pointers, suggestions?

[Mike]

If it runs better when you pull your choke then it is not getting enough fuel. It has plenty of air. I would pull the carb back off and clean all of the ports using a bristle from a wire brush. Run it through all of them and then spray through them with carburetor cleaner after you have them cleaned. Watch the float as well to see if it is working properly through its entire range of motion.

[Bazooo guy]

Did you replace the fuel filter ? Also check the fuel hose is clear and flowing properly.

[eddieb1965]

My favorite carb cleaning tool is a set of torch tip cleaners.You can select the right size cleaner for the passage you are working on. Eddie

[WhoIsJohnGalt]

I did replace the fuel filter and fuel seems to pulse into the carburetor OK ( I have no way to measure, but it "looks" like it is doing fine ). I ordered a replacement float assembly, should get here Monday. Will let you know how it goes.

[Coop]

You have dirt in your main jet. Clean out the main jet with a small piece of wire and then blow some air thru it.

Coop

[fmints]

I would surely recheck you carbs. Those jets can get the slightest amount of sediment in it that will make carb act up. The carb still acts up, check you fuel pump. Member WMCOUNCIL has a max II that was bogging down, but erratically in sperts, it took us a little bit to find out that his fuel pump had a major short in it. Under vibration or bumps it would short out for a few and then come back on. It was solved by getting an aftermarket electric fuel pump like this Mr. Gasket® 42S - Fuel Pump Electric. We purchased ours from Oreilly's, NAPA, and Advanced Auto. Im running the same one on my Hustler as a back up, just in case. I had it as my main fuel pump when I had my 16hp in the Hustler and it didn't skip a beat because it only sends amount of fuel that is needed,, no flooding. I hope this helps you!

[WhoIsJohnGalt]

Thanks guys. I will be cleaning out the carb again this wekend. I may go ahead and order that fuel pump since the machine has sat stored for so long, it is very likely to have crud or deteriorated.

[WhoIsJohnGalt]

The replacement float arrived early today. I tore down the carb, cleaned every orifice once more, blew everything with air. Replaced the float. Reinstalled the carburetor and air filter. Fired up nicely. A couple of idle adjustments and she now takes throttle better than ever! I took the kids out in the woods and Down our lane. Max climbs better than ever, motor over logs like a dream, and raced down our dirt road faster than ever.

To recap: I changed he spark plugs, fuel filter, added Seafoam to the fuel tank, blew out the air filter with compressed air, dismantled the carb and cleaned every opening with carb cleaner then replaced the float. I adjusted the idle speed and had to reset the jet screws.

[Mike]

That's good to hear. Now you can really enjoy your Max.